VellumPdf.Signing 1.5.4

VellumPdf

A modern, dependency-free PDF generation library for .NET 10, implemented clean-room from the open ISO 32000 standard.

Status: stable. The public API is locked (analyzer-enforced) and the library targets .NET 10. Core features are CI-validated — including PDF/A-2a/2b/2u and PDF/UA-1 conformance proven on every push with veraPDF.

Why VellumPdf

• Zero runtime dependencies. The core is built entirely on the .NET base class library — no native binaries, no third-party packages. (The optional signing package is the sole exception: it uses System.Security.Cryptography.Pkcs.)
• AOT- and trim-ready. Ships as managed DLLs; ideal for Native AOT, trimming, containers, and serverless. A Native-AOT smoke test guards this.
• Unicode-first text. Embeds and subsets TrueType and OpenType-CFF fonts, emits composite (CID) fonts with subset tags, and writes ToUnicode maps so output stays searchable and copy-paste-able.
• Two API tiers. A low-level canvas for precise drawing, and a high-level document/layout engine with paragraphs, headings, lists, tables, images, and automatic pagination.
• Built for the hard standards. PDF/A-2a (accessible archival) and PDF/UA-1 (universal accessibility) are implemented and CI-validated with veraPDF, alongside PDF/A-2b/2u, PAdES digital signatures, and interactive AcroForms.
• Permissive license. Apache-2.0 — free to use in proprietary products.

Packages

Quick start

dotnet add package VellumPdf.Layout

using VellumPdf.Document;          // PdfConformance
using VellumPdf.Fonts;             // Standard14
using VellumPdf.Layout;            // Document
using VellumPdf.Layout.Core;       // TextStyle
using VellumPdf.Layout.Elements;   // Paragraph, Heading
using VellumPdf.Layout.Elements.Table; // TableElement

// Basic document — defaults to A4.
using var doc = new Document();
doc.SetDefaultFont(new TextStyle { Font = Standard14.Helvetica, FontSize = 11 });
doc.Add(new Heading("Hello, world!"));
doc.Add(new Paragraph("Generated with VellumPdf — no native dependencies."));
doc.Save("hello.pdf");

// PDF/A-2b archival document. PDF/A requires every glyph to come from an
// embedded font, so load a TrueType font and use it for all text.
using var archive = new Document { Conformance = PdfConformance.PdfA2b };
var font = archive.LoadTrueTypeFont("/path/to/DejaVuSans.ttf");
var style = new TextStyle { FontRef = font, FontSize = 12 };

archive.Add(new Paragraph("This document validates as PDF/A-2b.", style));

var table = new TableElement { DefaultCellStyle = style };
table.SetColumnWidths(200, 200);
table.AddHeaderRow().AddCell("Item").AddCell("Value");
table.AddRow().AddCell("Format").AddCell("PDF/A-2b");
archive.Add(table);

archive.Save("archive.pdf");

Low-level Kernel API

For precise canvas control, bypass the Layout engine and write directly to the PDF content stream:

using VellumPdf.Canvas;    // PdfCanvas
using VellumPdf.Document;  // PdfDocument, PageSize
using VellumPdf.Fonts;     // Standard14

using var doc = new PdfDocument();
var page = doc.AddPage(PageSize.A4);
var font = doc.UseFont(Standard14.Helvetica);
var canvas = new PdfCanvas(page);

canvas
    .BeginText()
    .SetFont(font, 12)
    .SetTextMatrix(1, 0, 0, 1, 72, 720)
    .ShowText("Hello from the Kernel API!")
    .EndText();

canvas.Finish();

using var stream = File.OpenWrite("kernel-hello.pdf");
doc.Save(stream);

For a full walkthrough of the canvas, graphics primitives, and font handling, see docs/kernel-guide.md.

Conventions

• Units. All coordinates and sizes are in PDF user-space points (1 pt = 1/72 inch). PageSize provides the common ISO-A sizes plus a PageSize.Mm(width, height) helper for custom millimetre dimensions.
• Synchronous I/O. Saving, signing, and the font/image loaders are synchronous by design for 1.0 — there is no async surface. Offload to Task.Run if you need to keep a thread free.

Validation & CI

Correctness is enforced on every push by running real external validators as CI oracles — a missing tool fails the build, so the gates can never silently skip:

• qpdf --check — structural integrity of every generated document type.
• pdftotext (poppler) — text-extraction round-trip proving ToUnicode maps.
• pdfsig (poppler) — signature validity for PAdES documents.
• veraPDF (official verapdf/cli Docker image) — strict PDF/A-2a/2b/2u and PDF/UA-1 conformance over embedded-font, table, image, and tagged documents. A non-compliant report fails CI with the full rule list attached.

Not yet / roadmap

Building

Requires the .NET 10 SDK.

dotnet build VellumPdf.slnx
dotnet test  VellumPdf.slnx

The veraPDF conformance gate runs automatically in CI; to reproduce it locally, install veraPDF (or use its Docker image) so the verapdf CLI is on your PATH, then run the oracle tests.

License & provenance

Licensed under the Apache License 2.0. VellumPdf is an original, independent implementation written solely from open published specifications; see NOTICE and docs/architecture.md.